- #1

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## Main Question or Discussion Point

They say that the unit bel was originally defined as:

[tex]B = \log\Big(\frac{P_1}{P_2}\Big) [/tex]

But then it turned out to be a large unit and people stated using decibels:

[tex]dB = 10\log\Big(\frac{P_1}{P_2}\Big) [/tex]

I don't get this. One decibel is one-tenth of a bel, then shouldn't dB be actually:

[tex]dB = \frac{1}{10}\log\Big(\frac{P_1}{P_2}\Big) [/tex]

?

[tex]B = \log\Big(\frac{P_1}{P_2}\Big) [/tex]

But then it turned out to be a large unit and people stated using decibels:

[tex]dB = 10\log\Big(\frac{P_1}{P_2}\Big) [/tex]

I don't get this. One decibel is one-tenth of a bel, then shouldn't dB be actually:

[tex]dB = \frac{1}{10}\log\Big(\frac{P_1}{P_2}\Big) [/tex]

?